This project involves an investigation of the distribution, chemistry, biosynthesis, and intermediary metabolism of sphingolipids. Details will be sought about the mechanisms of enzymatic hydroxylation and desaturation in the synthesis of sphingolipid bases, and the mode of action of an inhibitor of sphingosine synthesis will be determined. New procedures will be developed for the isolation and chemical characterization of antigenic constituents of normal canine kidney and heart, and will be applied to a study of changes that may accompany acute rejection of these organs in transplant recipients. Studies will be continued on the intermediary metabolism of the glycosphingolipids that accumulate in Fabry's disease and a genetic defect of ganglioside metabolism resembling Tay-Sachs disease (Sandhoff's disease). These investigations will include studies of the metabolic fate of globoside and other glycosphingolipids in the membranes of reticulocytes and senescent erythrocytes as well as turnover studies of the plasma pools of these lipids. The alpha-galactosidase specific for hydrolysis of galactosylgalactosylglucosylceramide and deficient in Fabry's disease will be purified from normal plasma and/or lysosomes. The enzyme will be used for an immunochemical approach to the isolation of defective protein from plasma of patients with Fabry's disease and for attempts to obtain clinical control in these patients by enzyme replacement. Cultured fibroblasts will be used to develop model systems for the sphingolipidoses, involving antibody inactivation of lysosomal hydrolases and tests of subsequent correction with enzymes added to the medium.